Genç, Ayten | Türer, Dilek

Proceedings | 2005 | Proceeding of the 9th International Conference on Environmental Science and Technology Vol B - Poster Presentations

Electrokinetic remediation experiments of metal contaminated soils (Pb, Zn, Cu) were performed by constructing a multiple anode electrode arrangement. In this arrangement, the electrokinetic unit was cylindrical and had three sections. The central cylinder was selected as the cathode well to minimize the extent of the basic environment by the cathode and the outer cylinder was selected as the anode to maximize the spread of the acidic environment generated by the anodes. Nine identical graphite rods were used as electrodes and eight of them were the anodes. The anode electrodes were placed in octagonal with respect to the cathode el . . .ectrode. In the experiments, a constant potential difference of 250 volt was applied to the electrodes and maintained for about 30 hours. In order to determine the removal efficiencies of metals as a function of distance from the electrodes the soil was divided into four sections. The metal amounts in each section were evaluated by adding the metal amounts at different fractions of the soil (i.e., exchangeable, sorbed, carbonate, organic and residual) that were obtained from by using a sequential extraction method. Experimental results showed that metals that were present in different fractions of soil could be removed or redistributed in different fractions of soil by the help of electric field. Depending on the sequential extraction results, the overall removal efficiencies of lead, zinc and copper from the soil were evaluated as 29%, 18% and 18%. In order to identify effects of electrode geometry on efficiency the electrokinetic remediation experiment was repeated by using a parallel plate electrodes configuration. In this case, the electrokinetic unit was rectangular and two identical graphite plates were inserted into the electrode compartments as the anode and the cathode electrodes. For lead, zinc and copper, higher removal efficiencies were obtained; numerically, 32%, 37% and 31%, respectively. Even though in theoretical analysis, higher performance is expected from the multiple anode arrangement, the presence of inactive electric field areas in the soil could be the main cause for the decrease in the removal efficiency values Daha fazlası Daha az

Altın, Ahmet | Değirmenci, Mustafa

Article | 2005 | SCIENCE OF THE TOTAL ENVIRONMENT337 ( 01.Mar ) , pp.1 - 10

Electrokinetic remediation is a very effective method to remove metal from fine-grained soils having low adsorption and buffering capacity. However, remediation of soil having high alkali and adsorption capacity via the electrokinetic method is a very difficult process. Therefore, enhancement techniques are required for use in these soil types. In this study, the effect of the presence of minerals having high alkali and cation exchange capacity in natural soil polluted with lead (II) was investigated by means of the efficiency of electrokinetic remediation method. Natural soil samples containing clinoptilolite, gypsum and calcite mi . . .nerals were used in experimental studies. Moreover, a sample containing kaolinite minerals was studied to compare with the results obtained from other samples. Best results for soils bearing alkali and high sorption capacity minerals were obtained upon addition of 3 mol AcH and application of 20 V constant potential after a remediation period of 220 h. In these test conditions, lead (II) removal efficiencies for these samples varied between 60% and 70% up to 0.55 normalized distance. Under the same conditions, removal efficiencies in kaolinite sample varied between 50% and 95% up to 0.9 normalized distance. (C) 2004 Elsevier B.V All rights reserved Daha fazlası Daha az

Türer, Dilek | Genç, Ayten

Article | 2005 | JOURNAL OF HAZARDOUS MATERIALS119 ( 01.Mar ) , pp.167 - 174

The electroremediation experiments were conducted on artificially polluted soils by introducing a single metallic contaminant (Pb, Zn and Cu) and multiple metallic contaminants (Pb + Zn + Cu). Based on sequential extraction results, it was observed that the removal efficiencies of lead, zinc and copper vary depending on types of contamination. When the soil was contaminated only by lead, the removal efficiency was found to be 48%. However, the removal efficiency of lead decreased to 32% when the soil was contaminated by the combination of lead, zinc and copper. Similar results were observed for zinc and copper. The corresponding rem . . .oval efficiency values for zinc and copper were 92% and 37%, and 34% and 31%, respectively. Effects of electrode geometry on the removal efficiency of metals were investigated by constructing a multiple anode arrangement. In this arrangement, the electrokinetic unit consists of three cylinders, which lie one inside the other, and the soil was placed in the middle cylinder. The central cylinder was the cathode well and the outer cylinder was the anode well, where eight identical anode electrodes were placed in octagonal with respect to the cathode electrode. By using this electrode arrangement in removal of metals from the soil contaminated with the combination of three metals (Pb + Zn + Cu), the removal efficiencies of lead, zinc and copper were found to be 29%, 18% and 18%, respectively. As it can be seen, these numerical values are much lower than the values that were obtained when the traditional two-plate electrode arrangement used in the electroremediation experiments (32%, 37% and 31%). (c) 2004 Elsevier B.V. All rights reserved Daha fazlası Daha az